The invention relates to a power management module. More particularly, the invention relates to a power management module dedicated to a portable phone such as a cellular phone.
Mobile and portable electronic devices such as cellular phones can be powered by small accumulators or removable batteries and such. As batteries store only a limited amount of electrical energy, the batteries have to be re-charged after a certain time of use and/or stand-by operation. To re-charge the battery of a conventional cellular phone, the cellular phone is connected to a charger with the battery coupled to the phone, or the battery is re-charged separately.
Besides this cordless battery operation, a cellular phone can be connected to a car battery while used in a car. When connected to the battery of the car, the cellular phone switches the internal power supply from the removable battery to the battery of the car. This conserves the electrical energy stored in the removable battery when other power sources are available.
Choosing between the car battery and the removable battery is one of the tasks usually performed by a cellular phone subsystem, hereinafter referred to as a power management system. The power management system includes techniques and mechanisms to efficiently operate the cellular phone, inter alia, for the purpose of extending battery life. Power management should be efficient, reliable and easy to implement, particularly, in cellular phones. That is, consumers demand even smaller and lighter cellular phones which offer longer operation time. However, these are often contradictory requirements, particularly as the battery is often heavier than the rest of a cellular phone.
The present invention provides a novel power management system which is, in a preferred embodiment, adapted for integration on a single chip. This allows implementation of an efficient power management system into a cellular phone without increasing the complexity of the cellular phone. The single-chip power management system comprises a control logic which communicates with a central processor and controls the power supply for sub-systems of the cellular phone. The control logic can be adapted to perform specific application specific tasks. For example, the control logic can be adapted to perform a self-test of the power management system by providing output power on a step-by-step basis and monitoring power consumption after each step, i.e., after providing power to an additional component.
An aspect of the invention involves an electronic, portable apparatus configured to be operable by a battery or an external power supply. The apparatus comprises a power management module, having input and output ports, and peripheral components. The power management module comprises several modules. A switching module is configured to select a supply voltage for the power management module. A module of voltage regulators, within this module each regulator is configured to provide selectively a voltage of a preset value at outputs of the power management module. A first voltage converter is configured to transform the selected supply voltage to an output voltage having a required value, if the preset value of the selected supply voltage is lower than the required value. A power-on-reset module is configured to provide for a predefined sequence of activation of the peripheral components. A control logic module which is associated with a communications interface, and which is configured to receive signals for controlling the module of voltage regulators and the power-on-reset module.
In one embodiment of the apparatus, the power management module comprises an interface which is adapted to communicate with an external memory device. Such a memory device may be a smart card storing user specific data. Such a smart card is particularly used in cellular phones operating according to mobile communications standards such as the Global System for Mobile Communications (GSM) and the Digital Communications System (DCS).
A further aspect of the invention involves a power management module for an electronic, portable apparatus which is configured to be operable by a battery and an external power supply. The power management module has input and output ports and comprises a switching module, voltage regulators, a first voltage converter, and a power-on-reset module. Control logic, also included in the power management module, is associated with a communications interface and receives signals for controlling the module of voltage regulators and the power-on-reset module.